1. Technical Field
One aspect of the present invention relates to a rubber composition for a tire. More particularly, one aspect of the present invention relates to a rubber composition for a tire imparted with a steering stability during high-speed traveling, a wet performance, a sustainability of a grip performance, a wear resistance, and a low rolling resistance, which surpass the conventional levels.
2. Related Art
There are a variety of performances required for a pneumatic tire for a high-performance automobile. Particularly required performances include an excellent steering stability during high-speed traveling, stability on a wet road surface (wet performance), wear resistance, and reduction of rolling resistance in order to improve a fuel consumption performance. Moreover, it is also required to enable inhibition of a change in tire performance (thermal degradation) even when travelling at high speed for a long period of time on Autobahn or around a circuit, and to excel at blow-out resistance.
Examples of conventionally known technologies to improve the steering stability during high-speed traveling or the wet performance include: to blend styrene-butadiene rubber having a high glass transition temperature with a rubber composition for a tire configuring a tread portion of a pneumatic tire; and to increase the blending amount of the carbon black or silica in the rubber composition for a tire. However, these technologies have the following problems: the rolling resistance decreases with an increase in amount of the carbon black. Moreover, when an amount of the silica is increased, the wear resistance decreases. Further, when the total amount of the carbon black and the silica is increased, the sustainability of a grip performance during high-speed travelling decreases. This leads to another problem that the tire tends to experience the performance degradation due to heat, and thus, the blow-out resistance further decreases.
Therefore, JP-A-2007-92086 proposes a tire tread rubber composition containing diene-based rubber with which cyclic polysulfide is blended. The rubber composition has had slightly improved steering stability, wet performance, sustainability of a grip performance, and low rolling resistance. However, the level of improvements does not satisfy the level required for a high-performance tire. Therefore, there is still room for further improvement. Moreover, the wear resistance of the rubber composition is not sufficient.
An object of one aspect of the present invention is to provide a rubber composition for a tire imparted with a steering stability during high-speed traveling, a wet performance, a sustainability of a grip performance, a wear resistance, and a low rolling resistance, which surpass the conventional levels.